In 2008, in a proof of principle study, Aurora Esquela-Kerscher and colleagues demonstrated for the first time that restoration of let-7b was able to inhibit lung cancer in vivo in an orthotopic mouse lung cancer model expressing KrasG12D, an activating mutation for Kras. This work provided strong evidence that let-7b works as a tumor suppressor in the lung and demonstrated the potential of let-7b as a potential miRNA-based therapeutic to treat lung cancer [83]. This evidence concerns the gene KRAS and lung cancer.